The Ultimate Guide to Alii (Orlistat)


Everything You Need to Know About Alli


Non-prescription Orlistat is sold under the brand name alli.  It was developed to help people who are dieting to lose weight faster and more easily, and to prevent regain after weight loss.   It is intended for use with a low fat, mildly reduced-calorie diet.


What are Orlistat and Alli?


Alli  belongs to a class of medications known as anti-obesity agents, specifically gastrointestinal lipase inhibitors, or “fat burners,” which work by preventing some of the fat in foods eaten from being absorbed in the intestines. This unabsorbed fat is then removed from the body in the stool.  

You may have heard of the prescription version of orlisat, called Xenical.  Xenical contains double the dosage of allii, and must be prescribed by your doctor.  Non-prescription alli® contains the same active ingredient (orlistat) as Xenical;  alli pills contain 60 mg of orlistat, while Xenical pills contain 120 mg.

The Food and Drug Administration (FDA) approved prescription orlistat in 1999. Prescription Xenical contains 120 mg of orlistat.


Over-the-counter alli, manufactured by GlaxoSmithKline, was approved in 2007.



Is Alli it Right for You?


Alli is meant for adults over 18, who have a Body Mass Index (BMI) of 25 or above.  


A BMI over 25 indicates overweight. If you’re not sure of your BMI, you can find it on the National Institute of Health’s BMI calculator



How Does Alli Work For Weight Loss?


In simple terms, alli is a fat blocker. The main ingredient in the pill (orlistat) binds with the digestive enzyme, pancreatic lipase, that would normally break down fat from the meal that you consumed. In attaching to this enzyme, alli prevents lipase from digesting about a quarter of the fat in your meal, allowing it to pass through the digestive system and out of the body, undigested. 

The result of alli’s binding action on lipase is fewer calories from dietary fat being absorbed by the body.


  • if you ate a 2000 calorie/day diet comprised of 30% fat, alli would create daily deficit of 200 calories.
  • if your meal contains 20 grams of fat, alli will prevent the absorption of 5 grams of fat.

Note that if you replace calories from fat by eating carbohydrates or protein, you will not get the full benefits of alli, so it’s important to watch your calories and fat intake at mealtimes.



 Clinical Studies


The active ingredient in alli, orlistat, has been the subject in over 100 clinical studies which makes orlistat one of the most thoroughly studied weight loss drugs in the world, used by more than 50 million people.  The studies have shown that alli, along with diet and exercise, results in greater weight loss than diet alone.

Alli is currently the only over-the-counter weight loss aid which is classified as a drug, therefore requiring approval by the U.S. Food and Drug Administration (FDA). 

No other over-the-counter weight loss supplements have this classification, which means they did not require a pre-market review or approval by the FDA.  Alli, however, has had to go through a rigorous testing and approval process.  


Research Summaries:


Orlistat-treated patients lost significantly more weight than placebo-treated patients, orlistat therapy produced less weight regain than placebo.  Several obesity-related risk factors improved significantly more with orlistat treatment than with placebo, and orlistat was generally well tolerated.

– January 2000,  published in Obesity Research


Orlistat therapy produces clinically significant weight loss, with improvements in glycemic control and cardiovascular disease risk factors, in overweight or obese patients with type 2 diabetes who have suboptimal metabolic control with insulin therapy.

– June 2002,  published in Diabetes Care


Orlistat is an effective and well-tolerated antiobesity drug, which can be employed as an adjunct to therapeutic lifestyle changes to achieve and maintain optimal weight.

– April 2011, published in the Indian Journal of Endocrinology and Metabolism


In addition to aiding weight loss, clinical trials have also shown that orlistat is associated with a reduction of serum LDL-C (the “bad” cholesterol), that is independent of the effect of weight loss alone.

Even after adjusting for percent weight loss, these studies found that subjects treated with orlistat sustained a greater reduction in serum LDL-C concentrations than those treated with placebo.  The mechanism responsible for this effect may be related to orlistat-induced inhibition of dietary cholesterol absorption.

“Orlistat has a cholesterol lowering efficacy independent of its weight reducing effect”.

– June 2004 study, published in Ailmentary Pharmacology and Therapeutics


Orlistat is a useful antiobesity drug for obese patients who cannot achieve weight loss with diet alone. Furthermore, the drug has beneficial effects on metabolic parameters. It reduces the incidence of T2DM [type 2 diabetes] in patients with impaired glucose tolerance and improves lipid variables. The drug decreases LDL-C levels to a greater degree than expected from weight loss alone. Consequently, the drug may be useful for diabetic or hyperlipidemic obese patients.

– 2009 study, published in Clinical Lipidology



Take 1 alli capsule with each meal.


Alli is meant to be taken three times a day with your meals.

For overweight adults 18 years and older:

  • Take 1 (60 mg) capsule with each meal containing fat.
  • Do not take more than 3 capsules daily.
  • Take a multivitamin once a daily at bedtime.◊


◊ Orlistat may reduce the absorption of some fat-soluble vitamins and beta carotene, so when you use orlistat, you should take a daily multivitamin that contains vitamins A, D, E, K, and beta-carotene.  Take the multivitamin once a day, 2 hours before or 2 hours after taking orlistat, or just it at bedtime.  I like Source Naturals’ Mega-One High Potency for its optimum dosage of the fat-soluble vitamins.



What to Eat When Taking Alli



While you are taking orlistat, your diet should contain no more than 30% fat, and each meal must be within your fat target to minimize the chances of diet-related side effects — generally, that’s between 12 and 18 grams of fat per meal.

Fats should not be eliminated entirely, though, as some dietary fat is needed for good health.  So don’t opt for a completely non-fat diet; it isn’t good for you, and it would negate any benefit from taking alli.


Low Fat Diet Tips


Following a low fat diet is crucial while taking alli. If you are new to watching your fat intake, I’ve included some tips to help get you started; otherwise, scroll down to “Cautions”.



Low Fat Grocery Shopping Tips


  • Read nutrition labels on food packages. They show the number of grams of fat per serving and calories per serving.
  • Eat a variety of lower-fat foods to get all the nutrients you need.
  • Eat plenty of plant foods (such as whole-grain products, fruits, and vegetables) and a moderate amount of lean and low-fat, animal-based food (meat and dairy products)
  • When you’re shopping, choose lean meats, fish, and poultry.
  • Other good low-fat sources of protein include dried beans and peas, tofu, low-fat yogurt, low-fat or skim milk, low-fat cheese, and tuna packed in water.
  • is a great source for checking the fat and other nutrients in foods.  You can also do a search for foods that are low in fat.


Low Fat Cooking Tips



  • Trim all visible fat and remove the skin from poultry.
  • Refrigerate soups, gravies, and stews, and remove the hardened fat on top before eating.
  • Bake, broil, or grill meats on a rack that allows fat to drip from the meat. Don’t fry foods with oil.
  • Sprinkle lemon juice, herbs, and spices on cooked vegetables instead of using cheese, butter, or cream-based sauces.
  • Try plain, nonfat or low-fat yogurt and chives on baked potatoes rather than sour cream. Reduced-fat sour cream still has fat, so limit the amount you use.


Low Fat Dining Out



  • Choose simply prepared foods such as broiled, roasted, or baked fish or chicken.
  • Avoid fried or sautéed foods, casseroles, and foods with heavy sauces or gravies.
  • Ask that your food be cooked without added butter, margarine, gravy, or sauce.
  • If you’re ordering salad, ask for low-fat dressing on the side.
  • Select fruit, angel food cake, nonfat frozen yogurt, sherbet, or sorbet for dessert instead of ice cream, cake, or pie.


I also recommend the book Secrets to Fat-Free Cooking by Sandra Woodruff.

This book is a classic among low fat cookbooks, and includes over 150 low- and no-fat dishes that are easy to prepare, taste delicious, and are high in nutritional value. It will help you master low-fat cooking, and provide your with some great ideas.


Secrets of Fat-Free Cooking by Sandra Woodruff, RD


Alli and Other Eating Plans


Alli is also compatible with most sensible, weight loss programs as long as the calories from fat are not above 30%.

So, for example, if you’re on NutriSystem®, Jenny Craig®, Weight Watchers® or another similar program, alli will still work. 

You’ll have to have to keep balance in mind, though;  alli is meant to be taken three times a day with well-balanced, reduced-calorie, low-fat meals — so if you like to save most of your points, fat or calories for a big splurge meal, alli might not be a good choice for you.  To minimize diet-related side effects with alli, each meal needs to be within your fat target.

The manufacturer also doesn’t recommend using alli with low carb, high fat diets (greater than 30% of calories from fat).




Before taking alli, tell your doctor if you have or have ever had:

  • An eating disorder such as anorexia or bulimia
  • Type 1 or type 2 diabetes
  • Kidney stones or kidney disease
  • Pancreatitis (inflammation of the pancreas)
  • Gallbladder disease
  • Thyroid disease
  • Liver disease
  • An organ transplant
  • Cholestasis (a condition where the flow of bile from the liver is blocked)
  • Malabsorption syndrome (a condition that causes problems with absorbing food)


Pregnancy and alli

  • Alli is dangerous to an unborn baby. Stop taking this medicine and call your doctor right away if you become pregnant.
  • The drug may make it harder for your body to absorb certain vitamins, which could affect a breastfeeding baby’s diet.
  • If you’re breastfeeding, talk to your doctor before taking Alli.



Side Effects


Orlistat works by preventing the absorption of some of the fat you eat, and when the fat passes out of your body, you may have bowel changes.  The most common are gastrointestinal (GI) and are referred to as diet-related side effects. These effects are related to the way you take the product and how much fat you consume when taking alli capsules.

It’s important to understand that you need to adopt a low-fat, healthy lifestyle to avoid these treatment effects — having gastrointestinal symptoms is a signal that you’re not staying within the dietary guidelines.

Not everyone who takes alli experiences a diet-related side effect. According to the manufacturer, studies show that almost 50% of people never experience a diet-related side effect. These effects tend to occur early on when you first start taking it, as your body adjusts to your diet and alli, and then subsides as your body adjusts. Even if you do not experience any side effects, alli is still working.


Product users on message boards say that keeping to a strict low fat diet, and adding plenty of fiber to their meals allowed them to avoid the bowel issues.


Common Side Effects

Tell your doctor if any of the following side effects are severe or don’t go away:

  • Oily, fatty, or loose stools
  • Gas with oily spotting
  • Oily spotting on underwear or clothing
  • Urgent need to have a bowel movement or an increased number of bowel movements
  • Stomach pain
  • Pain in the rectum
  • Irregular menstrual cycles
  • Anxiety
  • Headache


Serious Side Effects

Tell your doctor right away if you experience any of the following serious side effects:

  • Hives, rash, or itching
  • Difficulty breathing or swallowing
  • Severe stomach pain
  • Severe fatigue or weakness
  • Nausea or vomiting
  • Loss of appetite
  • Pain in the upper right part of your stomach
  • Dark-colored urine or bloody urine
  • Light-colored stools
  • Yellowing of the eyes or skin (jaundice)


Effect of alli on the Liver


You may have seen some information on various websites warning that alli is toxic to the liver. If you’ve read the story about my Mother in my article “Why You Should Worry About Fatty Liver,” you know I’m all about protecting liver health.

I scoured the studies on orlistat, and found that the liver toxicity warnings around the web have been taken out of context, and are not really accurate.

According to the FDA,  there were 13 reported liver injuries during the evaluation period between April 1999 and August 2009.  These 13 reports were out of an estimated 40 million people worldwide who had used Xenical or alli.  The FDA summarizes that:

  • One U.S. case with alli and 12 foreign cases with Xenical reported between 1999 and 2009 out of an estimated 40 million people worldwide who have used Xenical or Alli.
  • Some patients in the reported cases also used other drugs or had other conditions that may have contributed to the development of severe liver injury.
  • Severe liver injury can occur in people not taking drugs and without a distinct cause.


The FDA has included a label warning, but has concludes that “… a cause and effect relationship of severe liver injury with orlistat use has not been established“. 

A newer study in March 2013, published in the British Journal of Medicine tested patients receiving orlistat and registered in the UK Clinical Practice Research Datalink, and linked with Hospital Episode Statistics data between 1999 and 2011.  Their results found that “Among 94 695 patients who received orlistat, 988 cases of acute liver injury were identified, with 335 confirmed as definite cases and 653 as probable cases. For all cases, an increased incidence of liver injury was detected during the 90 day period before orlistat was first started”. 

They concluded that:

“The incidence of acute liver injury was higher in the periods both immediately before and immediately after the start of orlistat treatment. This suggests that the observed increased risks of liver injury linked to the start of treatment may reflect changes in health status associated with the decision to begin treatment rather than any causal effect of the drug”.




Tell your doctor about all prescription, non-prescription, illegal, recreational, herbal, nutritional, or dietary drugs you’re taking, especially:

  • Anticoagulants (blood thinners) such as warfarin (Coumadin)
  • Cyclosporine (Neoral, Sandimmune)
  • Medicines for diabetes such as glipizide (Glucotrol), glyburide (DiaBeta, Micronase), metformin (Glucophage), and insulin
  • Medicines to control blood pressure
  • Medicines for seizures
  • Medicines for thyroid disease such as levothyroxine (Synthroid)
  • Any other medications for weight loss


Storage and Disposal of Alii


Keep alli in the container it came in, tightly closed, and out of reach of children.

Alli capsules should be stored at 20-25 degrees C (or 68-77 degrees F), and you should protect alli from excessive light, humidity and temperatures over 30 degrees C (or 86 degrees F).  Don’t store alli in the bathroom, where it can get too warm.

As with all unneeded medications, it should be disposed of in ways to ensure that pets, children, and other people cannot consume them. Don’t flush this medication down the toilet; instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. The caps on alli are intended to be child-proof, but to protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.


In Case of An Overdose


In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at  

If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, call emergency services at 911 right away.



Final Thoughts


Alli won’t make up for poor eating habits or an unhealthy lifestyle, but if you use it properly, it will help you absorb less calories from the fat in your meals.

If you’re interested in reading about alli user experiences, there are about 3000 consumer reviews on Amazon.


Hey!  Blogging can be a lonely business … I’d love to hear your thoughts!

Drop me a comment below! 

Follow me on Twitter @FancyNewMe

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